# Why is ROS Publisher not publishing?

I am currently trying to write a Python ROS program which can be executed as a ROS node (using rosrun) that implements the defs declared in a separate Python file arm.py (available at: https://github.com/nortega1/dvrk-ros/...). The program initially examines the current cartesian position of the arm. Subsequently, when provided with a series of points that the arm must pass through, the program calculates a polynomial equation and given a range of x values the program evaluates the equation to find the corresponding y values.

Within the arm.py file there is a publisher `set_position_cartesian_pub`

that sets the Cartesian position of the arm as follows:

```
self.__set_position_cartesian_pub = rospy.Publisher(self.__full_ros_namespace + '/set_position_cartesian', Pose, latch = True, queue_size = 1)
```

The issue is that the publisher `set_position_cartesian`

is not publishing the values of the newPose to the robot - can anyone figure out what the issue might be? I can confirm that the def lagrange correctly calculates the values of the x and y coordinates, which are printed out to the terminal via the command `rospy.loginfo(newPose)`

. Any help would be greatly appreciated as I've been trying to solve this issue for the last 2 days!

```
#! /usr/bin/python
import rospy
import sys
from std_msgs.msg import String, Bool, Float32
from geometry_msgs.msg import Pose
from geometry_msgs.msg import PoseStamped
from geometry_msgs.msg import Vector3
from geometry_msgs.msg import Quaternion
from geometry_msgs.msg import Wrench
class example_application:
def callback(self, data):
self.position_cartesian_current = data.pose
rospy.loginfo(data.pose)
def configure(self,robot_name):
self._robot_name = 'PSM1'
ros_namespace = '/dvrk/PSM1'
rospy.Subscriber('/dvrk/PSM1/position_cartesian_current', PoseStamped, self.callback)
self.set_position_cartesian = rospy.Publisher('/dvrk/PSM1/set_position_cartesian', Pose, latch=True, queue_size = 10)
rospy.sleep(3)
rospy.init_node('listener', anonymous=True)
rospy.spin()
def lagrange(self, f, x):
total = 0
n = len(f)
for i in range(n):
xi, yi = f[i]
def g(i, n):
g_tot = 1
for j in range(n):
if i == j:
continue
xj, yj = f[j]
g_tot *= (x - xj) / float(xi - xj)
return g_tot
total += yi * g(i, n)
return total
def trajectoryMover(self):
newPose = Pose()
points =[(0.0156561,0.123151),(0.00715134,0.0035123151),(0.001515177,0.002123151),(0.0071239751,0.09123150)]
xlist = [i*0.001 for i in range(10)]
ylist = [self.lagrange(points, xlist[i])*0.001 for i in range(10)]
for x, y in zip(xlist, ylist):
newPose.position.x = x
newPose.position.y = y
newPose.position.z = 0.001
newPose.orientation.x = 0.001
newPose.orientation.y = 0.001
newPose.orientation.z = 0.005
newPose.orientation.w = 0.002
rospy.sleep(1)
self.set_position_cartesian.publish(newPose)
rospy.loginfo(newPose)
rospy.spin()
def run(self):
# self.home()
self.trajectoryMover()
if __name__ == '__main__':
try:
if (len(sys.argv) != 2):
print(sys.argv[0] + ' requires one argument, i.e. name of dVRK arm')
else:
application = example_application()
application.configure(sys.argv[1])
application.run()
except rospy.ROSInterruptException:
pass
```